Engine will not crank over when I push start button nothing?

This sounds like you have a battery that is weak and needs to be replaced. Lets test it to see how it does.

https://www.2carpros.com/articles/car-battery-load-test

If it passses the test then I would check the starter motor trigger wire.

Here is a guide to show you how, look toward the bottom of the guide:

https://www.2carpros.com/articles/car-cranks-but-wont-start

If it tests bad here is a guide to help you see what it will take to change it out.

https://www.2carpros.com/articles/how-to-replace-a-starter-motor

You will need to raise the car up safely.

https://www.2carpros.com/articles/jack-up-and-lift-your-car-safely

From the sound of it, the system is not seeing a problem with theft deterrent. The only other suggestion would be to install a scan tool and check for codes, and valid communications with all modules. One other thing you might try, is disconnecting both battery cables, shorting them together for a minute or two, reconnecting and attempting start. If there is a locked up module in the system disrupting the communication line, this procedure would correct that.

Here is how you can clear the security system:

https://www.2carpros.com/articles/how-to-reset-a-security-system

Please let us know what happens.

Cheers

It could be a possibility that your scanner is not getting enough voltage to work did you try the battery test?

See if that helps, and reply to post.

If it continuously displays 'shift to park' with the key on, perhaps it is reading that it is in another gear. What happens if you turn the key on and move the shifter, what does the display indicate? If it will change on the display, try selecting neutral, and see if the vehicle will start then. There is a bulletin that may apply, it references checking the transmission connector for terminal issues. I have included it for your reference. I am not certain on the aftermarket scan tool, you would know more than I would on its compatibility, but the fact it is not communicating may be telling you something. I work at a GM dealer, and use their equipment, so when there is a communication issue, I can be almost certain it is a problem with the vehicle.

#PIC4740B: No Crank Multiple Warning Telltales ON Trans Shift Hard - (Nov 19, 2008)

Subject: No Crank, Multiple Warning Telltales On, Trans Shifts Hard

Models: 2008-2009 Cadillac CTS w/ Automatic Transmission

2007-2009 Cadillac SRX w/ 6-Speed Transmission

2006-2007 Cadillac STS w/ 6-Speed Transmission

2008- 2009 Cadillac STS

2006-2008 Cadillac STS-V

This PI was superseded to update model years. Please discard PIC4740A.

The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.

Condition/Concern:
Some customers may comment about one or more of the following concerns.

†The vehicle will not crank over and start.

†Multiple warning telltales illuminate

†The transmission shifts hard

†The door locks cycle while driving

The diagnostic system check may reveal one or more of the DTC listed below are stored. The transmission control module (TCM) or engine control module (ECM) may not communicate with the scan tool. The cause may be unseated pins in the transmission connector.

C0242
ECM Indicated TCS Malfunction

C0561
System Disabled Information Stored

P0575
Cruise Control Switch Signal Circuit

P0615
Starter Relay Control Circuit

P0700
Transmission Control Module (TCM) Requested MIL Illumination

P0856
Traction Control Torque Request Circuit

P1629
Theft Deterrent Fuel Enable Signal Not Received

P2544
Transmission Torque Request Circuit

U0073
Controller Area Network (CAN) Bus Communication

U0100
Lost Communication With ECM/PCM

U0101
Lost Communication With TCM

U0121
Lost Communication With Anti-Lock Brake System (ABS) Control Module

U0140
Lost Communication With Body Control Module

U2100
Controller Area Network (CAN) Bus Communication

U2105
Lost Communication With Engine Control Module (ECM)

U2106
Lost Communication With Transmission Control Module (TCM)

Recommendation/Instructions:
Inspect the transmission connector terminal connections. Disconnect the connector and carefully tug on each wire to ensure the pins are fully seated. A side load on the wires may cause a false positive lock. Repair the connections as necessary.

Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.

GM bulletins are intended for use by professional technicians, NOT a "do-it-yourselfer". They are written to inform these technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions, and know-how to do a job properly and safely. If a condition is described, DO NOT assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See your GM dealer for information on whether your vehicle may benefit from the information.

WE SUPPORT VOLUNTARY TECHNICIAN CERTIFICATION

The TCM is in the transmission. When did you check the battery?

The gear range should always display on the information display. I have an 2007 in my stall right now and confirmed this. If you can find out why the gear range is not present, than you will probably find the problem with no start. As far as the scan tool communications, it sounds like you may have an issue. I am not 100% certain, since I have no experience with that particular scan tool. The gear range is input to the TCM via the internal mode switch, which is also in the transmission. Is the mode switch faulty? I am not certain. Since you can not validate it through the TCM data. I would think that the vehicle would not drive, shift, or even move with no TCM functioning. The transmission is all electronic. As well as checking the transmission connector for backed out pins, terminal tension may be another thing to consider, as well as shorts to ground somewhere in the harness. The way the high speed LAN architecture is laid out, the ECM is the last in line, followed by the TCM which is next to last. Modules on the high speed line are option dependent, but the ECM and TCM are last in all cases. What this means is that you have wiring going down the rear of the engine over the bell-housing, and back to the ECM along the same path. If there is a short in a line, it will take the system down. I can send you schematic and you can check wires, but there are three possibilities. Based on whether the vehicle is just option UE1, UE1 and F55, or UE1 F55 and K59. The option sticker is under the spare tire cover.

Here it is, hopefully it is legible.

It designates an internal fault of the appropriate control module it is stored in. In most all cases, it is repaired simply by module replacement. Which ECU stored the fault?

If it is stored in the ECM, then yes, you would have to replace the ECM. You did not specify what module it was stored within.

The IPC is right in front of the driver, the instrument panel cluster. The HVAC module is also the control head for the climate system.

I would not replace it at this point, I would focus more on why you cannot communicate with the TCM or ECM. The IPC and the HVAC are on the low speed LAN communication line and should not cause a no start with just a general ECU malfunction code. If it is in fact in the HVAC module, which was one of the possibilities you listed, there is a bulletin on that.
#PIC4025: History DTC B1000 Set in HVAC - keywords battery CCP climate code control panel - (Apr 14, 2006)

Subject: History DTC B1000 Set In HVAC

Models: 2005-2006 Cadillac STS

The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.

Condition/Concern:
Technicians may discover a history DTC set in HVAC Climate Control Panel. This DTC can be set if power is lost to the HVAC control head due to a battery or HVAC Control Head disconnect.

Recommendation/Instructions:
This is a normal condition. There will be no symptoms associated with this code. Technicians should clear all DTCs if power is cycled to the HVAC control head.